1. Field of the Invention
The present invention relates to a current collector for a fuel cell which is capable of collecting electricity generated from a fuel cell and a stack structure having the same in which a plurality of fuel cells are stacked.
2. Discussion of Related Art
Generally, a fuel cell is a power generator which includes an air electrode layer and a fuel electrode layer on both sides of an electrolytic layer and generates electricity by flowing air including oxygen and a fuel gas including hydrogen to the air electrode layer and the fuel electrode layer, respectively, and electrochemically reacting the hydrogen and the oxygen through an ion conductive phenomenon in the electrolytic layer.
The above fuel cell has eco-friendly characteristics such as a highly efficient and pollution free power generator which has simple energy conversion steps and generates energy by theoretically oxidizing hydrogen, and thus, research is being actively processed recently.
In particular, a solid oxide fuel cell (SOFC) among the fuel cells is a fuel cell which uses a ceramic as an electrolytic material and operates at a high temperature in a range of 600 to 1,000° C., and has various advantages of the highest efficiency and lowest pollution among various types of fuel cells such as other molten carbonate fuel cell (MCFC), a phosphoric acid fuel cell (PAFC), a polymer electrolyte fuel cell (PEFC), and/or the like, and capability of combined generation without a fuel reformer.
A single cell is composed of a pair of an electrolyte layer, an air electrode layer, and a fuel electrode layer of the above fuel cell, and since the single cell generates a voltage less than about 1 V and does not have effectiveness, a technology of increasing a generated voltage by multiply stacking a plurality of single cells as a stack structure is being highlighted.
The above stack structure indispensably requires a plurality of interconnectors which electrically connect the single cells therebetween and have channels each configured to flow the air and the fuel gas at a position in contact with the air electrode layer and the fuel electrode layer of the single cell. Here, a charge collector is additionally disposed between the interconnector and the single cell to efficiently collect electricity generated from the single cells.
However, as a conventional charge collector is manufactured in a mesh shape weaved by wires, and since the conventional charge collector electrically point contacts with the interconnector and the single cells at junction portions at which the wires cross, charge collecting efficiency is decreased and loads are excessively concentrated on the point contact portions, thereby generating damage such as a crack in the single cells. In particular, the charge collector is bent by the load concentration by the above point contact at a channel portion of the interconnector, and is then separated from the single cell at the channel portion, thereby more decreasing the charge collecting efficiency.
Also, since the above charge collector has an uneven surface in a structure, a coating which prevents generation of a poisoning material on the surface thereof is not uniformly formed, thereby causing difficulty in a manufacturing process.